Nature versus Nurture

Nature versus Nurture is the novel’s argument over whether a person’s character is inherited, acquired through experience, or made by an interaction between the two. It gives scientific language to the family’s most intimate fears: a genetic mutation is proposed as a source of aggression, while an attachment diagnosis raises questions about childhood care. Neither account supplies a definitive explanation of Jacob Barber, and their unresolved tension makes certainty itself part of the conflict.

The environmentalist ideal

The novel introduces the environmental pole through a quotation attributed to John F. Watkins in Principles of Behaviorism (1913). Watkins imagines taking a healthy infant, regardless of ancestry, race, talent, or predilection, and shaping him through training, time, and a properly controlled environment into an artist, soldier, doctor, lawyer, priest, or thief. The infant, in this formulation, is equally capable of all these outcomes. Human possibility appears radically open: conduct is made rather than inherited.

That sweeping claim arrives as an epigraph to the section titled “It’s Different for Mothers,” giving the abstract debate a pointed domestic setting. The epigraph treats the environment as something that can be controlled and character as something that can be deliberately produced. The family’s experience, however, offers no such clean experiment. The past cannot be controlled or replayed, and parents cannot infer a single cause from the child they know.

Genetic risk and aggression

The debate becomes immediate when Andrew Barber explains that scientists want to test for a mutation called MAOA Knockout. He describes it as a genetic mutation that might code the body to become more aggressive in certain environments. The qualification matters: the claim is not that genes mechanically dictate violence, but that a genetic factor might influence behavior under particular environmental conditions.

The exchange places heredity inside the family’s practical crisis. Andrew asks for DNA, and the explanation identifies the test’s purpose; the mutation is not presented as an answer already established by the narrative. It is a hypothesis under investigation. The phrase “in certain environments” also prevents the genetic account from standing apart from experience: even the proposed biological risk depends on context, leaving inheritance and environment entangled rather than cleanly opposed.

Attachment, care, and uncertainty

Dr. Elizabeth Vogel’s discussion of reactive attachment disorder makes early experience another possible source of explanation. She says the diagnosis is relatively new, uncommon, difficult to diagnose, and difficult to treat, and that little research has been done. In the account she gives, disruption of ordinary emotional attachment in infancy may affect how a child relates to others; the described behaviors can include aggression, rage, lying, defiance, lack of remorse, and cruelty, as well as overfamiliarity, hyperactivity, and self-endangerment.

The diagnostic theory initially appears to point toward “pathogenic care,” usually mistreatment or neglect by a parent or caregiver. But Dr. Vogel stresses that the meaning of the term is controversial and that recent research suggests an attachment disorder might arise without deficient caregiving. Some children, she explains, may be temperamentally vulnerable, so that even minor disruptions—day care or being passed among caregivers too often—could be enough to trigger a disorder. The possibility of predisposition thus re-enters an account that seems, at first, to place responsibility wholly on the environment.

Laurie Barber connects that possibility to a concrete fact in Jacob’s childhood: he attended day care from three months old, while both parents worked, and she stopped teaching when he was four. Dr. Vogel tells Laurie there is not enough knowledge to presume cause and effect, that there is no reason to think neglect caused the disorder, and that Jacob may simply have been unusually vulnerable. Her reassurance does not mollify Laurie. The scene shows how a provisional theory can become a personal accusation even when the expert explicitly warns against drawing that conclusion.

An unresolved account of character

The competing explanations offer no simple verdict. Watkins’s epigraph imagines a child molded by a controlled environment; the genetic test asks whether inherited biology could heighten aggression in certain surroundings; the attachment discussion proposes that early care may matter while acknowledging temperament, incomplete research, and uncertain causation. Each account supplies a framework, but none demonstrates that it explains Jacob.

The novel’s force lies in keeping those frameworks in contact without allowing them to resolve into a formula. Biological possibility does not establish destiny, and the fact of day care does not establish parental failure. The scientific vocabulary can sharpen the family’s questions while leaving the central one unanswered: what made Jacob who he is? Nature versus Nurture therefore functions less as a contest with a winner than as a structure of uncertainty, in which evidence about genes and childhood can be interpreted but cannot, by itself, settle identity or responsibility.